The role of surface area to volume ratio in cellular processes is significant as it affects diffusion and the overall efficiency of cellular functions. Smaller cells have a higher surface area to volume ratio, allowing for more efficient exchange of materials with the environment, such as nutrients and waste products. As cells grow larger, the surface area increases at a slower rate than the volume, which can limit the cell's ability to obtain necessary resources or expel waste. Hence, maintaining an optimal size is crucial for cellular health and function.